There are several kinds of dependents you can claim. But for HH they need to be related to you. You might be confusing the fact that to be a regular dependent they have to live with you, except for HH a related person does not have to live with you. But that doesn't mean any dependent qualifies you for HH.
Who is a qualifying person for Head of Household. See IRS pub 501 page 9 and table 4 on page 10.
https://www.irs.gov/pub/irs-pdf/p501.pdf
Example 3—your friend. Your friend lived
with you all year. Even though your friend may
be your qualifying relative if the gross income
and support tests (explained later) are met,
your friend isn't your qualifying person for head
of household purposes because your friend isn't
related to you in one of the ways listed under
Relatives who don't have to live with you, later.
